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Shape-memory resin, molded product composed of the resin, and method of using the molded product

a technology of shape memory and resin, which is applied in the field of shape memory resin, molded product composed of resin, and method of using molded product, can solve the problems of no mechanical properties, polylactic acid has not yet become widespread, and polylactic acid is more expensive than petroleum-based resins, etc., and achieves excellent shape memory properties, high mechanical strength, and high toughness.

Inactive Publication Date: 2013-06-25
NEC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0020]It is an object of the present invention to provide: a shape-memory resin, which is formed from a polylactic acid derivative, has an excellent shape memory-property, high strength, and high toughness, and high durable products, for example, electronic equipments, particularly wearable electronic equipments of which shapes can be reformed easily by users; and products thereof. It is another object of the present invention to provide: a shape-memory resin, in which a biodegradable resin is used to reduce an environmental load when discarded; and a molded products thereof.Means for Solving the Problems
[0021]As a result of intensive studies, the present inventors have found that a resin having a three-dimensional structure, in which a polylactic acid derivative having two or more functional groups is cross-linked using a flexible polymer having two or more functional groups capable of forming a cross-linking site and having Tg of lower than 30° C., and a linker, has excellent deformation-fixing ability and shape-recovering ability and also has excellent strength. The inventors have completed the present invention based on such findings.
[0023]In addition, the present invention relates to: a molded product, which is shaped into an original shape using the above-mentioned shape-memory resin at a temperature lower than the degradation temperature of the shape-memory resin, wherein the original shape is memorized; or a molded product shaped into the original shape, wherein the original shape thereof is deformed at a temperature that is equal to or higher than the glass transition temperature (Tg) of the shape-memory resin, and is then cooled to a temperature lower than the glass transition temperature, so that the deformed shape can be fixed.
[0024]The shape-memory resin of the present invention is able to provide: a shape-memory resin, which is formed from a polylactic acid derivative, a flexible polymer having Tg of lower than 30° C., and a linker, which has an excellent shape-memory property, high mechanical strength, and high toughness, and high durable products, for example, electronic equipments, particularly wearable electronic equipments of which shapes can be reformed easily by users; and a molded product thereof. Moreover, using a biodegradable resin, an environmental impact can be reduced when the resin is discarded.

Problems solved by technology

However, polylactic acid is more expensive than petroleum-based resins, and it has no mechanical properties other than environmental compatibility, which are superior to those of petroleum-based resins.
Due to such problems, polylactic acid has not yet become widespread.
Thereby, the thermoplastic type shape-memory resin is inferior in shape recovering property to the thermosetting type shape-memory resin.
However, since such crosslink by irradiation with an active energy ray does not adopt a perfect three-dimensional structure, the shape-memory performance of the concerned shape-memory resin is lower than that of a thermosetting resin.
Moreover, since it requires high costs for equipments and a shaping process has a certain limit, it is difficult to produce a large product and the like.
Polylactic acid having such cross-linking site by a thermo-reversible reaction has good mechanical strength, however it does not have sufficient toughness.
However, the strength of such polylactic acid is not sufficient to be applied to durable products.

Method used

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  • Shape-memory resin, molded product composed of the resin, and method of using the molded product
  • Shape-memory resin, molded product composed of the resin, and method of using the molded product
  • Shape-memory resin, molded product composed of the resin, and method of using the molded product

Examples

Experimental program
Comparison scheme
Effect test

example 1

Synthesis of Terminal Hydroxy Polylactic Acid

[0070]2220 g of polylactic acid (Terramac; manufactured by Unitika Ltd.) and 76.8 g of sorbitol were melted and mixed at 210° C. for 12 hours to carry out a transesterification, so as to obtain an ester compound. A solution obtained by dissolving this ester compound in 5 L of chloroform was poured into an excessive amount of methanol, and it was reprecipitated, so as to obtain terminal hydroxy polylactic acid [R1]. Its number average molecular weight was 7300, and its Tg was 46.8° C.

[0071]

[Synthesis of Flexible Polymer (Terminal Hydroxy Polybutylene Succinate (PBS))]

[0072]117 g of succinic anhydride and 128 g of 1,4-butanediol were heated at 190° C. for 4 hours, and they were then further heated under a reduced pressure for 2 hours, to carry out a dehydration condensation reaction, thereby obtaining an ester compound. A solution obtained by dissolving this ester compound in 200 mL of chloroform was poured into an excessive amount of metha...

example 2

[0080]As a flexible polymer, polybutylene succinate [R3] (Bionore: manufactured by Showa Highpolymer Co., Ltd.) (number average molecular weight=21300; Tg=−32° C.) was used.

[0081]

[0082][R1] and [R3] were melted and mixed (170° C.) at the composition ratio shown in Table 2, and lysine triisocyanate used as a linker was then added to the mixture. The linker was added thereto, such that the amounts of terminal hydroxy groups in [R1] and [R3] could be equimolar to the amounts of isocyanate groups in the linker. Thereafter, the mixture was subjected to compression molding at 170° C. for 2 hours, so as to obtain a polylactic acid cross-linked product. The results obtained by evaluating the flexural strength, elongation at break, Tg, and shape-memory property of the obtained polylactic acid cross-linked product are shown in Table 3.

[0083]

TABLE 3Composition (wt %)Amount of linker addedPhysical properties of cross-linked PLAPLA(mg / polymer 1 g)BendingElongation(TerminalFlexible polymerLinkers...

example 3

Synthesis of Maleimide Group-Containing Polylactic Acid

[0084]25.0 g of β-alanine, 28.9 g of maleic anhydride, and 100 mL of THF were stirred in a nitrogen atmosphere at a room temperature for 24 hours. Thereafter, a solid was filtrated to obtain maleamide propionic acid [R4] (yield: 96%). Subsequently, 22.1 g of [R4], 6.11 g of orthophosphoric acid, 0.0937 g of BHT, 100 mL of xylene, 300 mL of toluene, and 20 mL of dioxane were each weighed, and they were then refluxed in a three-necked flask for 3 hours. The reaction temperature was 116° C. Thereafter, the reaction solution was cooled to a room temperature, and the solvent was then distilled away under a reduced pressure. The obtained solid was dissolved in chloroform. Thereafter, the chloroform was distilled away from this solution under a reduced pressure, and the solid was then recrystallized from diethyl ether, so as to obtain maleimide carboxylic acid [R5].

[0085]

[0086]6.25 g of [R5] was dissolved in 90 mL of chloroform, and th...

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Abstract

There are provided: a shape-memory resin, which is formed from a polylactic acid derivative thereby enabling reduction of an environmental load, has an excellent shape-memory property, high strength, and high toughness, and with which a molded product with high durability, for example, an electronic equipments, particularly a wearable electronic equipments capable of freely changing the shape thereof or the like, can be shaped; and a molded product thereof. The shape-memory resin of the present invention has a three-dimensional structure, in which a polylactic acid derivative having two or more functional groups capable of forming a cross-linking site is cross-linked using a flexible polymer having a glass transition temperature (Tg) lower than 30° C. and having two or more functional groups capable of forming a cross-linking site, and a linker.

Description

TECHNICAL FIELD[0001]The present invention relates to: a shape-memory resin, which reduces environmental impact, performing shape-memory property, flexural strength and high elongation at break; a molded product using the same; and a method of using the molded product.BACKGROUND ART[0002]In recent years, concern about environmental problems has been increasing. Under such circumstances, in order to reduce carbon dioxide that causes global warming, and as an effective material alternative to petroleum that is an exhaustible resource, biomass-based resin, particularly, polylactic acid, has received attention. Polylactic acid has a relatively high melting point (150 to 180° C.), and it has strength comparable to that of a polystyrene. Thus, it is greatly expected that such polylactic acid will become widely used. However, polylactic acid is more expensive than petroleum-based resins, and it has no mechanical properties other than environmental compatibility, which are superior to those...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): C08G63/91
CPCC08G18/10C08G18/4202C08L67/04C08G18/4238C08G18/4283C08G18/771C08G18/8064C08J3/246C08G18/282C08L67/02C08K5/29C08G2280/00C08J2367/04C08L2666/18
Inventor SHIMURA, MIDORIINOUE, KAZUHIKOIJI, MASATOSHI
Owner NEC CORP
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